SRC/slaqz4.f(3)

NAME
SRC/slaqz4.f

SYNOPSIS

  Functions/Subroutines
subroutine slaqz4 (ilschur, ilq, ilz, n, ilo, ihi, nshifts, nblock_desired, sr, si, ss, a, lda, b, ldb, q, ldq, z, ldz, qc, ldqc, zc, ldzc, work, lwork, info)
SLAQZ4

Function/Subroutine Documentation

  subroutine slaqz4 (logical, intent(in) ilschur, logical, intent(in) ilq, logical, intent(in) ilz, integer, intent(in) n, integer, intent(in) ilo, integer, intent(in) ihi, integer, intent(in) nshifts, integer, intent(in) nblock_desired, real, dimension( * ), intent(inout) sr, real, dimension( * ), intent(inout) si, real, dimension( * ), intent(inout) ss, real, dimension( lda, * ), intent(inout) a, integer, intent(in) lda, real, dimension( ldb, * ), intent(inout) b, integer, intent(in) ldb, real, dimension( ldq, * ), intent(inout) q, integer, intent(in) ldq, real, dimension( ldz, * ), intent(inout) z, integer, intent(in) ldz, real, dimension( ldqc, * ), intent(inout) qc, integer, intent(in) ldqc, real, dimension( ldzc, * ), intent(inout) zc, integer, intent(in) ldzc, real, dimension( * ), intent(inout) work, integer, intent(in) lwork, integer, intent(out) info)

SLAQZ4

Purpose:

    !>
    !> SLAQZ4 Executes a single multishift QZ sweep
    !>

Parameters
    ILSCHUR

    !>          ILSCHUR is LOGICAL
    !>              Determines whether or not to update the full Schur form
    !>

    ILQ

    !>          ILQ is LOGICAL
    !>              Determines whether or not to update the matrix Q
    !>

    ILZ

    !>          ILZ is LOGICAL
    !>              Determines whether or not to update the matrix Z
    !>

    N

    !>          N is INTEGER
    !>          The order of the matrices A, B, Q, and Z.  N >= 0.
    !>

    ILO

    !>          ILO is INTEGER
    !>

    IHI

    !>          IHI is INTEGER
    !>

    NSHIFTS

    !>          NSHIFTS is INTEGER
    !>          The desired number of shifts to use
    !>

    NBLOCK_DESIRED

    !>          NBLOCK_DESIRED is INTEGER
    !>          The desired size of the computational windows
    !>

    SR

    !>          SR is REAL array. SR contains
    !>          the real parts of the shifts to use.
    !>

    SI

    !>          SI is REAL array. SI contains
    !>          the imaginary parts of the shifts to use.
    !>

    SS

    !>          SS is REAL array. SS contains
    !>          the scale of the shifts to use.
    !>

    A

    !>          A is REAL array, dimension (LDA, N)
    !>

    LDA

    !>          LDA is INTEGER
    !>          The leading dimension of the array A.  LDA >= max( 1, N ).
    !>

    B

    !>          B is REAL array, dimension (LDB, N)
    !>

    LDB

    !>          LDB is INTEGER
    !>          The leading dimension of the array B.  LDB >= max( 1, N ).
    !>

    Q

    !>          Q is REAL array, dimension (LDQ, N)
    !>

    LDQ

    !>          LDQ is INTEGER
    !>

    Z

    !>          Z is REAL array, dimension (LDZ, N)
    !>

    LDZ

    !>          LDZ is INTEGER
    !>

    QC

    !>          QC is REAL array, dimension (LDQC, NBLOCK_DESIRED)
    !>

    LDQC

    !>          LDQC is INTEGER
    !>

    ZC

    !>          ZC is REAL array, dimension (LDZC, NBLOCK_DESIRED)
    !>

    LDZC

    !>          LDZ is INTEGER
    !>

    WORK

    !>          WORK is REAL array, dimension (MAX(1,LWORK))
    !>          On exit, if INFO >= 0, WORK(1) returns the optimal LWORK.
    !>

    LWORK

    !>          LWORK is INTEGER
    !>          The dimension of the array WORK.  LWORK >= max(1,N).
    !>
    !>          If LWORK = -1, then a workspace query is assumed; the routine
    !>          only calculates the optimal size of the WORK array, returns
    !>          this value as the first entry of the WORK array, and no error
    !>          message related to LWORK is issued by XERBLA.
    !>

    INFO

    !>          INFO is INTEGER
    !>          = 0: successful exit
    !>          < 0: if INFO = -i, the i-th argument had an illegal value
    !>

Author
    Thijs Steel, KU Leuven

Date
    May 2020

Definition at line 210 of file slaqz4.f.

Author

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